Small fixes
- Add .mha to the "Volume" bloc of the default config. Fix #141 (closed)
- Correct a greedy rexexp that was opening all .vt* file. Fix #146 (closed)
- Resynchronize hotkeys lists. Fix #147 (closed) #139 (closed)
- Add a how to use section
- Show a drop file suggestion with the filename actor. Fix #137 (closed)
- Simplify the hotkeys logic to avoid complex cases. Fix #138 (closed) #142 (closed)